KR101812027B1 - Method and system for estimating location of a plurality of underwater robot connercted by cable - Google Patents

Method and system for estimating location of a plurality of underwater robot connercted by cable Download PDF

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Publication number
KR101812027B1
KR101812027B1 KR1020150185487A KR20150185487A KR101812027B1 KR 101812027 B1 KR101812027 B1 KR 101812027B1 KR 1020150185487 A KR1020150185487 A KR 1020150185487A KR 20150185487 A KR20150185487 A KR 20150185487A KR 101812027 B1 KR101812027 B1 KR 101812027B1
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South Korea
Prior art keywords
cable
target object
image
length
estimating
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KR1020150185487A
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Korean (ko)
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KR20170075930A (en
Inventor
유선철
김주환
조현우
표주현
조한길
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포항공과대학교 산학협력단
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Priority to KR1020150185487A priority Critical patent/KR101812027B1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1656—Programme controls characterised by programming, planning systems for manipulators
    • B25J9/1664—Programme controls characterised by programming, planning systems for manipulators characterised by motion, path, trajectory planning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J5/00—Manipulators mounted on wheels or on carriages
    • B25J5/02—Manipulators mounted on wheels or on carriages travelling along a guideway
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/10—Programme-controlled manipulators characterised by positioning means for manipulator elements
    • B25J9/104—Programme-controlled manipulators characterised by positioning means for manipulator elements with cables, chains or ribbons
    • B25J9/1045—Programme-controlled manipulators characterised by positioning means for manipulator elements with cables, chains or ribbons comprising tensioning means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1674—Programme controls characterised by safety, monitoring, diagnostic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1679—Programme controls characterised by the tasks executed
    • B25J9/1684—Tracking a line or surface by means of sensors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1694—Programme controls characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
    • B63C11/00—Equipment for dwelling or working underwater; Means for searching for underwater objects
    • B63C11/48—Means for searching for underwater objects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B2201/00—Signalling devices
    • B63B2201/18—Sonar

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Robotics (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Ocean & Marine Engineering (AREA)
  • Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)

Abstract

A method for estimating the position of an underwater robot operating in water is provided. A method for estimating the position of an underwater robot includes a first body positioned in water or a water surface and a second body movable in a state of being connected to the first body by a cable, Adjusting a length of the cable so that the second body can be close to the target object, setting a search area to grasp the position of the second body in consideration of the length of the cable, The method comprising the steps of: selecting an object larger than the size of the second body in the second body, determining a second body among the selected objects in comparison with movement of the second body, and estimating the position of the second body.

Description

Field of the Invention < RTI ID = 0.0 > [0001] < / RTI > A method and system for locating a plurality of underwater robots connected by a cable,

The present invention relates to a method and system for estimating the position of a plurality of underwater robots connected by cables.

In recent years, as interest in the oceans has increased, activities such as marine exploration have been increasing. As these activities are increasing, many kinds of detectors such as underwater robots which are mainly used for underwater exploration are being developed.

It is important to understand the current location of underwater robots. Since it is not possible to use radio waves in an underwater environment, navigation devices such as GPS can not be used to determine the current position.

Also, in the case of a mission that is difficult to solve by using one underwater robot in water, there are cases where a plurality of underwater robots can be solved through mutual cooperation among underwater robots.

However, since the inertia moment and the dead zone of the propeller thrust are different according to the sizes of a plurality of underwater robots, it is difficult to estimate the positions and attitudes of a plurality of underwater robots due to different working radius and control accuracy.

An embodiment of the present invention is to provide a position estimation method and system for real-time estimation of a three-dimensional position and an attitude of an underwater robot when performing an object survey in water.

According to an aspect of the present invention, there is provided a method for estimating a relative position between a first body positioned on water or a water surface and a second body movable to a target body while being connected to a cable by the first body, Aligning the second body; Adjusting a length of the cable so that the second body is close to a target object; Setting a search area to determine a position of the second body in consideration of the length of the cable; Changing pixels of the image in the set search area that are lighter than the predetermined threshold value to white, and binarizing all pixels darker than a predetermined threshold value to black; Selecting regions larger than a predetermined size in the binarized image as objects; Determining the second body among the selected objects by comparing the velocity of the second body with the velocity of the second body, and estimating a position of the second body that is grasped, wherein the first body and the second body Wherein the step of aligning the first body includes moving the first body to the target body, measuring a distance from the point where the first body moves through the imaging sonar coupled to one side of the first body to the target body And aligning headings of the first body and the second body so as to match the yaw values.

At this time, in the step of adjusting the length of the cable so that the second body approaches the target object, the cable can be released or rolled through the winch installed in the first body.

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In this case, the step of adjusting the length of the cable so that the second body is close to the target object may further include a step of making the cable between the first body and the second body to be taut.

The step of tightening the cable between the first body and the second body may further include confirming whether the cable is tight through the tension sensor installed on the cable end.

At this time, in setting the search area to grasp the position of the second body in consideration of the length r of the cable, the distance L of the search area of the second body considering the length r of the cable ) May satisfy r-α <L <r + α and the irradiation angle θ may be θmin <θ <θmax.

In this case,? Is the major axis length of the second body, and the irradiation angle? May be within 90 degrees? Max -? Min.

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The predetermined size v may be A * 0.9 <V <A * 1.1 based on the size (A) of the pixel area calculated by considering the error of the cable length r and the error in the image.

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At this time, the predetermined threshold value may be 0 when the darkest pixel value is 0 in the image, and may be 0.5 when the brightest pixel value is 1.

At this time, in the step of selecting the second body among the selected objects in comparison with the motion of the second body, the selected objects are tracked and a velocity vector of the objects is obtained using the movement distance and the time difference between frames of the image The object corresponding to the speed of the second body can be selected.

At this time, in the step of estimating the position of the second body, when the direction angle (?) Of the selected second body, the depth (D) of the first body and the depth (d) The coordinates of the position of the second body may be as follows.

Figure 112015126618341-pat00001

At this time, the target object is at least one of the objects located on the underwater floor, and the size of the first body may be larger than that of the second body.

According to another aspect of the present invention, A second body connected to the first body by a cable and movable to the target body while being connected to the first body by the cable; An imaging sonar installed at one side of the first body to acquire underwater images of the target object and the second body; An image portion for converting pixels in the underwater image acquired through the imaging sonar to pixels having a brightness greater than a predetermined threshold value to white and for converting all pixels darker than a predetermined threshold value to black to binarize the image, And a control unit for selecting the regions as objects and comparing the speed of the second body with the speed of the second body to determine the second body among the selected objects and to estimate the position of the second body .

At this time, a pressure sensor installed at one side of the first body and the second body and measuring the pressure applied to one side of the first body and the second body, . &Lt; / RTI &gt;

The gyrosensor may be mounted on the first body and the second body to measure a rotation angle of the first body and the second body to determine a yaw angle of the first body and the second body. have.

The apparatus may further include a tension sensor installed at an end of the cable to measure a tension applied to the cable, and a screw installed in the second body to tighten the cable.

In this case, the first body may be provided with a winch that is installed at one side of the first body so that the cable can be wound or unwound, and the first body can transmit power or control signals to the second body through the cable .

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The position estimation method and system according to an embodiment of the present invention can estimate the three-dimensional position and posture of the underwater robot in real time by allowing the underwater robot to move around the object to be surveyed without accumulating the position error.

In addition, the position estimation method and system according to an embodiment of the present invention allow the underwater robot to stay around an object without departing from a designated route even when a long time object survey is performed.

1 is a flowchart illustrating a method of estimating a position of a submersible robot according to an embodiment of the present invention.
2 is a schematic view showing a state where a second body is attached to a first body used in a method of estimating the position of a submersible robot according to an embodiment of the present invention.
FIG. 3 is a schematic view showing movement of a second body used in a method for estimating the position of a submersible robot according to an embodiment of the present invention toward a target object.
4 is a schematic view showing a first body used in a method of estimating a position of an underwater robot according to an embodiment of the present invention.
5 is a schematic view showing a second body used in a method of estimating the position of an underwater robot according to an embodiment of the present invention.
6 is a schematic view showing an imaging sonar used in a method of estimating the position of an underwater robot according to an embodiment of the present invention.
FIG. 7 is a schematic view showing an image of a target object obtained through an imaging sonar in a state where a second body is attached to a first body used in a method of estimating the position of an underwater robot according to an embodiment of the present invention.
8 is a schematic view illustrating an image of a second body and a target object obtained through an image sonar in a state in which a second body used in a method for estimating a position of a submersible robot according to an embodiment of the present invention is moving toward a target object; to be.
9 is a schematic diagram showing a search area of a method of estimating a position of an underwater robot according to an embodiment of the present invention.
FIG. 10 is a schematic diagram showing a position estimation calculation of a method of estimating a position of an underwater robot according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Hereinafter, a method for estimating the position of a submersible robot and a system thereof according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 is a flowchart illustrating a method of estimating a position of a submersible robot according to an embodiment of the present invention.

Referring to FIG. 1, a method for estimating the position of an underwater robot according to an embodiment of the present invention includes aligning a first body and a second body (S10), aligning a length of a cable A step S30 of setting a search area to grasp the position of the second body in consideration of the length of the cable, a step S40 of selecting objects larger than the size of the second body in the search area, Comparing the speed of the second body to determine a second body of the selected objects (S50), and estimating a position of the detected second body (S60).

The position estimating method according to an embodiment of the present invention estimates the relative position and posture of the second body 30 based on the first body 10 in real time to quickly and accurately move the target body 3 do.

2 is a schematic view showing a state where a second body is attached to a first body used in a method of estimating the position of a submersible robot according to an embodiment of the present invention. FIG. 3 is a schematic view showing movement of a second body used in a method for estimating the position of a submersible robot according to an embodiment of the present invention toward a target object.

2 and 3, a position estimation system 1 for estimating a position of a submersible robot according to an embodiment of the present invention includes a first body 10, an imaging sonar 20, Two bodies 30 may be included.

2 and 3, in an embodiment of the present invention, the second body 30 is connected to the first body 10 by a cable 15a and is connected to the first body by a cable, ) And can be used when precise underwater work such as docking and sample collection is required

Meanwhile, in the embodiment of the present invention, the first body 10 and the second body 30 may be submerged robots located on the water or water surface, but the present invention is not limited thereto, vehicles and submarines.

At this time, the first body 10 and the second body 30 can be used for exploration of seabed resources, lifting work of a sunken vessel, oil removal work, installation of a submarine cable, and repair of an underwater structure.

In addition, the first body 10 and the second body 30 need to move freely in three-dimensional water. For this purpose, an attitude control device for adjusting the attitude and a movement control device for controlling the movement in the three- .

4 is a schematic view showing a first body used in a method of estimating a position of an underwater robot according to an embodiment of the present invention. 5 is a schematic view showing a second body used in a method of estimating the position of an underwater robot according to an embodiment of the present invention.

4, the first body 10 includes a first sensor unit 11, a first control unit 13, a connection unit 15, a video unit 17, 19).

At this time, the first sensor unit 11 is connected to the first controller 13 of the first body 10 to acquire position information related to the posture, the moving direction, and the moving speed of the first body. The information on the attitude of the first body 10 acquired by the first sensor unit 11 includes information on the roll angular velocity, the pitch angular velocity, and the yaw angular velocity of the first body. do.

The information on the moving direction and the moving speed of the first body 10 acquired by the first sensor unit 11 is obtained by the following equation using the surge linear velocity, sway linear velocity and heave line velocity of the first body, Includes information on speed.

Meanwhile, in an embodiment of the present invention, the first sensor unit 11 may include a pressure sensor (not shown) and a gyro sensor (not shown). At this time, the pressure sensor is installed on one side or inside of the first body 10 to measure the depth D where the first body is placed in the water by measuring the pressure applied to the first body.

In an embodiment of the present invention, the gyro sensor may be installed on one side or inside of the first body 10 to measure the yaw angle of the first body by measuring the rotation angle of the first body.

In an embodiment of the present invention, a DVL (Doppler velocity log) sensor (not shown) is installed at one side or inside of the first body 10 to detect a surge and a sway on the bottom surface of the first body, The position of the first body can be grasped by measuring the relative linear velocity of the first body.

Referring to FIG. 4, the first controller 13 can calculate and determine the current position of the first body 10 based on the information acquired by the first sensor unit 11. FIG.

Meanwhile, in an embodiment of the present invention, the connection part 15 may include a cable 15a and a winch 15b. 3, one end of the cable 15a is connected to the first body 10 and the other end is connected to the second body 30 so that the second body can move in a state of being connected to the first body by a cable have.

At this time, the cable 15a may be a special cable having a neutral buoyancy so as to minimize the influence on buoyancy. In addition, a tension sensor (not shown) may be installed at the end of the cable 15a to measure the tension applied to the cable so that the cable can be held tight.

In the embodiment of the present invention, the first body 10 may supply power to the second body 30 through the cable 15a or may transmit a control signal of the first controller 13 to the second controller (33).

In an embodiment of the present invention, the winch 15b may be installed at a lower end of the first body 10, for example, as shown in FIG. 3, to allow the cable 15a to be wound or unwound have.

At this time, the winch 15b includes an encoder (not shown) inside the winch 15b, and the distance between the first body 10 and the second body 30 can be accurately measured by measuring the amount of rotation of the winch 15b .

The first propeller 19 may be installed on one side of the first body 10 to move the first body 10 and the second body 30 in the vicinity of the target point 3, And maintains the position and posture of the first body 10 while the second body 30 approaches the target point 3. [

3, the second body 30 may be connected to the first body 10 by a cable 15a, and may move to the target body 3 in a state where the first body 10 is connected to the cable. At this time, the second body 30 may be a movable underwater robot, but it is not limited thereto, and may be an AUV and a remote control submersible instead of an underwater robot if necessary.

In an embodiment of the present invention, the second body 30 is smaller than the first body 10 and is attached to the first body 10 to move over a long distance, and when a precise underwater operation such as docking and sample collection is required Can be used.

Referring to FIG. 5, in an embodiment of the present invention, the second body 30 may include a second sensor unit 31, a second control unit 33, and a second propeller 35.

At this time, the second sensor unit 31 is connected to the second control unit 33 of the second body 30 to obtain speed information related to the posture, the moving direction, and the moving speed of the second body. The information on the posture of the second body 30 acquired by the second sensor unit 31 includes information on the roll angular velocity, the pitch angular velocity, and the yaw angular velocity of the second body. do.

The information on the moving direction and the moving speed of the second body 30 acquired by the second sensor unit 31 may be obtained from the surge linear velocity, sway linear velocity, and heave line velocity of the second body, Includes information on speed.

Meanwhile, in an embodiment of the present invention, the second sensor unit 31 may include a pressure sensor (not shown) and a gyro sensor (not shown). At this time, the pressure sensor is installed on one side or inside of the second body 30 to measure the pressure d applied to the second body, thereby measuring the depth d of the second body located in the water.

Also, in an embodiment of the present invention, the gyro sensor may be installed on one side or inside of the second body 30 to measure the yaw angle of the second body by measuring the rotation angle of the second body.

5, the second controller 33 controls the second controller 33 through the information acquired by the second sensor 31 and the information acquired by the connection unit 15 and the image unit 17 of the first body 10, The current position of the body 30 can be calculated and determined. The second control unit 33 may control the second propeller 35 based on the control command received from the first control unit 13 of the first body 10.

Meanwhile, in an embodiment of the present invention, the second propeller 35 may be installed on one side of the second body 30 to adjust the position and posture of the second body 30 such that the cable 15a is tightened .

In one embodiment of the present invention, the target object 3 may be at least one of the objects located in the underwater floor, but is not limited thereto, and may be a landmark in the water. Landmarks are targets that can be identified in the water to locate underwater robots that operate under water.

6 is a schematic view showing an imaging sonar used in a method of estimating the position of an underwater robot according to an embodiment of the present invention. FIG. 7 is a schematic view showing an image of a target object obtained through an imaging sonar in a state where a second body is attached to a first body used in a method of estimating the position of an underwater robot according to an embodiment of the present invention. 8 is a schematic view illustrating an image of a second body and a target object obtained through an image sonar in a state in which a second body used in a method for estimating a position of a submersible robot according to an embodiment of the present invention is moving toward a target object; to be.

Referring to FIG. 6, in an embodiment of the present invention, the imaging unit 17 may include an imaging sonar 20. 7, the imaging sonar 20 may be installed at a lower end of the first body 10 to acquire an underwater image of the target object 3, for example, one side of the first body 10. At this time, the second body 30 is attached to the first body 10, and the image of the target object 3 may be expressed in white.

Referring to FIG. 8, the imaging sonar 20 can acquire an underwater image of the target object 3 and the second body 30. At this time, the second body 30 moves toward the target object 3, and the images of the second body and the target object may be expressed in white.

In one embodiment of the present invention, the imaging sonar 20 may be mounted on one side or inside of the first body 10 to obtain an ultrasound image. At this time, the imaging sonar 20 can acquire an underwater image by receiving a signal that the transmitted sound wave is reflected on the underwater object

In the meantime, in the step S10 of aligning the first body and the second body in the embodiment of the present invention, the first body is moved to the target body (S11), the imaging body A step S12 of measuring the distance from the point where the first body moves to the target object, and a step S13 of matching the yaw angular values of the first body and the second body.

In order to accurately measure the distance between the first body 10 and the second body 30 in the step of aligning the first body and the second body in the embodiment of the present invention, And the head of the second body.

Meanwhile, in the step S10 of moving the first body to the target body in the embodiment of the present invention, the first body is moved to the vicinity of the target body by using the navigation sensor installed inside the first body 10. [ At this time, the second body 30 is attached to one side of the first body 10.

2, in the step S12 of measuring the distance from the point where the first body moves through the imaging sonar connected to one side of the first body to the target object, the second body 30 is moved to the target object 3), the distance from the first body 10 to the target object is measured using the imaging sonar 20. At this time, the first body 10 can maintain its position near the target object 3.

Meanwhile, in step S13 of matching the yaw angular values of the first body and the second body, the distance between the first body 10 and the second body 30 is accurately measured, In order to grasp the relative position of the body, align the prongs of the first body and the second body to match the yaw values.

In the step S20 of adjusting the length of the cable so that the second body can approach the target object in the embodiment of the present invention, the cable 15a is loosened through the winch 15b installed on the first body 10 The length of the cable is adjusted so that the second body 30 can approach the target object 3, and the length is measured in real time using an internal encoder.

Meanwhile, the step S20 of adjusting the length of the cable so that the second body can approach the target object may further include a step S21 of making the cable between the first body and the second body tight. The cable between the first body 10 and the second body 30 may be accurately measured through the cable 15a in step S21 in which the cable between the first body and the second body is tightened. .

At this time, step S21 of making the cable between the first body and the second body to be tightened further includes a step (S22) of checking whether the cable is tight through a tension sensor (not shown) provided at an end of the cable 15a can do.

9 is a schematic diagram showing a search area of a method of estimating a position of an underwater robot according to an embodiment of the present invention. FIG. 10 is a schematic diagram showing a position estimation calculation of a method of estimating a position of an underwater robot according to an embodiment of the present invention.

9 and 10, in the step S30 of setting the search area to determine the position of the second body considering the length of the cable according to the embodiment of the present invention, the first body 10 and the second body The distance L and the angle? Of the search area of the second body are set in consideration of the length r of the cable 15a, which is the distance between the bodies 30.

In this case, the distance L in the search area may be a range smaller than the cable length r and larger by?. That is, r-α <L <r + α. In addition, the irradiation angle? In the search area may be? Min <? <? Max.

At this time, the released cable length r can be obtained by measuring the number of revolutions of the winch using an encoder included in the winch 15b. At this time, the distance L of the search region may be r -? <L <r +?, Where? May be a value corresponding to the long axis length of the second body 30.

Further, the imaging sonar 20 may have a constant irradiation angle? In the search area. In this case, the irradiated angle range of the irradiation angle may be θmin <θ <θmax, and the irradiation angle size θmax - θmin may have a value within 90 degrees.

On the other hand, the magnitude of the irradiation angle [theta] max - [theta] min may be 29 degrees, but is not limited thereto and may vary depending on the purpose of the search area and the imaging sonar 20.

 In addition, the step S40 of selecting an object larger than the size of the second body in the search area may include a step S41 of binarizing the image in the set search area, And selecting a larger area as an object (S42).

In an embodiment of the present invention, in step S41 of binarizing an image in the set search area, all pixels brighter than a predetermined threshold value are changed to white, and pixels darker than a predetermined threshold value can be changed to black have.

Referring to FIG. 9, the second body 30 and the object in the water may be changed to white in a region including the second body and the object underwater as pixels lighter than the predetermined threshold value. In addition, in the region where the second body 30 and the underwater object are not included, all the pixels darker than the predetermined threshold value can be changed to black.

At this time, the predetermined threshold value for binarization changes according to the environment, and there are various methods for calculating this threshold value. However, if the binarization technique is simplified in the embodiment of the present invention, the darkest pixel value is set to 0 in the image of the imaging sonar 20 and the predetermined threshold value is set to 0.5 Lt; / RTI &gt;

On the other hand, in the step S42 of selecting the regions larger than the predetermined size (v) in the binarized image as the object, the regions above the predetermined size in the region where the second body 30 and the underwater object are changed to white are all objects .

At this time, the size of the cross section of the second body 30 matched in the image of the imaging sonar 20 can be measured in advance to determine the size of the second body. It is also possible to calculate the size of the pixel area of the cross section of the second body 30 which varies in the image of the imaging sonar 20 according to the distance between the first body 10 and the second body 30, .

In this case, the predetermined size (V) is a size within ± 10% based on the size (A) of the pixel area calculated by considering the error of the cable length (r) and the image, that is, A * 0.9 <V <A * 1.1. &Lt; / RTI &gt; At this time, only the region having a predetermined size (V) or more can be selected as a candidate object of the second body.

Meanwhile, in step S50 of grasping the second body among the selected objects in comparison with the velocity of the second body, the velocity vectors of the objects are obtained using the movement distance and the time difference between frames of the image by tracking the selected objects, And grasps the object corresponding to the speed of the body 30.

Referring to FIG. 10, in step S60 of estimating the position of the second body detected in the embodiment of the present invention, the direction angle? Of the selected second body 30, the depth of the first body D And the depth d of the second body are calculated to calculate the position of the second body relative to the first body.

Here, the coordinates of the x second body , y second body, and z second body are as follows.

Figure 112015126618341-pat00002

Meanwhile, the position estimation method according to an embodiment of the present invention can accurately estimate the relative position of the second body 30 based on the first body 10, thereby improving the control accuracy.

In addition, the position estimation method according to an embodiment of the present invention estimates the current position of the second body 30 relative to the first body 10 in real time, and makes it possible to quickly and accurately move the target body 3 .

The position estimation method and system according to an embodiment of the present invention can estimate the three-dimensional position and posture of the underwater robot in real time by allowing the underwater robot to move around the object to be surveyed without accumulating the position error.

In addition, the position estimation method and system according to an embodiment of the present invention allow the underwater robot to stay around an object without departing from a designated route even when a long time object survey is performed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: Position estimation system 3: Target object
10: first body 11: first sensor part
13: first control section 15:
15a: Cable 15b: Winch
17: image part 19: first propeller
20: Imaging sonar 30: Second body
31: second sensor unit 33: second control unit
35: Second propeller

Claims (20)

A method for estimating a relative position of a first body positioned in water or a water surface and a second body movable to a target object while being connected to the first body by a cable,
Aligning the first body and the second body;
Adjusting a length of the cable so that the second body is close to a target object;
Setting a search area to determine a position of the second body in consideration of the length of the cable;
Changing pixels of the image in the set search area that are lighter than the predetermined threshold value to white, and binarizing all pixels darker than a predetermined threshold value to black;
Selecting regions larger than a predetermined size in the binarized image as objects;
Determining the second body among the selected objects by comparing the velocity of the second body with the velocity of the second body;
Estimating a position of the second body,
Wherein aligning the first body and the second body includes moving the first body to the target object, moving the first body through the imaging sonar coupled to one side of the first body, Measuring a distance to the target object, and aligning headings of the first body and the second body to match a yaw value. delete The method according to claim 1,
And adjusting the length of the cable so that the second body approaches the target object, the cable is loosened or wound through the winch installed in the first body. The method of claim 3,
Wherein adjusting the length of the cable so that the second body is close to the target object further comprises: tensioning the cable between the first body and the second body. 5. The method of claim 4,
Wherein the step of tensioning the cable between the first body and the second body further comprises checking whether the cable is tight through a tension sensor installed on the cable end. The method according to claim 1,
The distance L of the search area of the second body may be determined considering the length r of the cable in the step of setting the search area to grasp the position of the second body in consideration of the length r of the cable, and the irradiation angle? is? min <? <? max. The method according to claim 6,
Wherein? Is a major axis length of the second body, and the irradiation angle? Is within 90 degrees from? Max -? Min. delete The method according to claim 1,
The predetermined size (v) is A * 0.9 <V <A * 1.1 based on the size (A) of the pixel area calculated by considering the error of the cable length (r) and the error in the image. delete The method according to claim 1,
Wherein the predetermined threshold value is 0.5 when the darkest pixel value in the image is 0 and the brightest pixel value is 1. The method according to claim 1,
Wherein the step of selecting the second body among the predetermined objects in comparison with the motion of the second body tracks the selected objects to obtain a velocity vector of the objects using the movement distance and a time difference between frames of the image, And selecting the object corresponding to the velocity of the two bodies. The method according to claim 1,
In the step of estimating the position of the second body, when the direction angle (?) Of the selected second body, the depth (D) of the first body, and the depth (d) 2 The coordinates of the position of the body are as follows.
Figure 112017071538512-pat00003
 The method according to claim 1,
Wherein the target object is at least one of objects located on the underwater floor, and the size of the first body is larger than the size of the second body. A first body positioned in water or on a surface of water;
A second body connected to the first body by a cable and movable to the target body while being connected to the first body by the cable;
An imaging sonar installed at one side of the first body to acquire underwater images of the target object and the second body;
An image portion for converting pixels in the underwater image acquired through the imaging sonar to brighten all of the pixels that are lighter than the predetermined threshold value and binarizing all pixels darker than the predetermined threshold value into black,
A controller for selecting a region larger than a predetermined size in the binarized image as an object and comparing the speed with the speed of the second body to grasp the second body among the selected objects and estimating the position of the second body; / RTI &gt; 16. The method of claim 15,
And a pressure sensor installed at one side of the first body and the second body to measure a depth of the first body and the second body by measuring a pressure applied to one side of the first body and the second body . 16. The method of claim 15,
And a gyro sensor installed on the first body and the second body to measure a yaw angle of the first body and the second body by measuring a rotation angle of the first body and the second body, . 16. The method of claim 15,
A tension sensor installed at an end of the cable to measure a tension applied to the cable,
And a propeller installed on the second body to cause the cable to be taut. 16. The method of claim 15,
And a winch installed at one side of the first body to wind or unwind the cable, wherein the first body includes a position estimation system for supplying power to the second body through the cable or transmitting a control signal, . delete
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